Valves are commonly used in devices that involve the transportation of a fluid. A typical type of valve, for example used in laboratory systems of moderate sizes, is the rotary valve.
Generally, a rotary valve has a stationary body, herein called a stator, which co-operates with a rotating body, herein called a rotor.
The stator is provided with a number of inlet and outlet ports. The ports are via bores in fluid communication with a corresponding set of orifices on an inner stator face. The inner stator face is an inner surface of the stator that is in fluid tight contact with an inner rotor face of the rotor. The rotor is typically formed as a disc and the inner rotor face is pressed against the inner stator face in rotating co-operation. The inner rotor face is provided with one or more grooves which interconnect different orifices depending on the rotary position of the rotator with respect to the stator.
Rotary valves can be designed to withstand high pressures (such as pressures above 25 MPa). They can be made from a range of materials, such as stainless steel, high performance polymeric materials and ceramics.
The number of inlets/outlets as well as the design of grooves in the rotor or the stator reflects the intended use of a specific valve.
A common type of multi-purpose valve has one inlet port (typically placed in the rotary axis of the valve) and a number of outlets ports that are placed equidistantly around the inlet port. The rotor has a single, radially extending groove that has one end in the rotary centre, thereby always connecting to the inlet, while the other end connects to any one of the outlets depending on the angular position of the rotor with respect to the stator. Such a valve is useful to direct a flow from the inlet to any of the outlets—one at a time.
More complicated arrangements, tailor-made to perform one or several specific tasks, are possible. For instance, rotary valves may be used to introduce a component into the fluid path of an analytical system.
In many instruments handling a flow of a liquid, such as liquid chromatography systems (LCS), there is sometimes a need to be able to either include or to bypass a component.
This situation is easily solved with a conventional 4-way double-path valve, schematically shown in FIGS. 1 and 2.
However, it would be beneficial to be able to integrate more functionalities such as the ability to reverse the flow through the component into a single valve. One reason for this would be to save cost (e.g. since there is need for one valve motor drive only in the case of an automatically operated valve). Another reason would be the possibility to shorten path lengths by integrating as much paths into the valve as possible, thereby reducing the need for interconnecting tubing.
Thus, there is a need for a multipurpose valve that can be used for many situations where components need to be connected to/disconnected from a main flow.